The present invention relates generally to digitally controlled ink pumps and in particular, to the use of digitally controlled ink pumps in what is known as a one-up arrangement of such pumps in an array which includes multiple, series rollers for applying ink to sheets of paper.
According to the invention, there are provided a plurality of ink pumps (or one page pack) for each of the colors to be printed according to the new technique. The page pack may be one pack, in the case of black ink only, or plural packs, in the case of color(s), with one pack for each color being run on the press.
With prior systems, using the force of a cam or screw, plural zones of adjustment in an inking blade were made, resulting from deflection of the blade within its zone of adjustment. Consequently, a system working by operating plural screws for each blade served to vary the distance between the roller and the blade. This required adjustment zones, which were affected to a certain extent by the neighboring zone of adjustment. In such an arrangement, zero ink flow from the reservoir to the roller could not be accomplished. Leakages of ink onto the roller always occurred, and especially at high speeds, blade and roller wear occurred during operation.
The adjustments made by prior art systems are also inherently speed sensitive. They do not always track the press speed correctly. The metering of ink by blade deflection uses the viscosity of the ink in the area between the ink and blade and roller to achieve a specific ink flow rate. As the press speed increases, the ink volume decreases in proportion to the flow. The flow is increased somewhat as more ink is pulled from the portal through the roller, but not sufficient to make up for the difference. As a consequence, ink settings must be made heavy during the startup phase, with the anticipation that under higher speeds, they will diminish correspondingly.
In many cases, the sites that have such zones will not hold adjustment at speed. These mechanisms may be worn, sticky or broken. It is desired to have a zone whose operation is scaled to the press speed. The existing adjustment of press mechanisms often requires a fineness of adjustment that is difficult to achieve. It is unrealistic to expect accuracy, when the slightest touch sends the control into a varied ink delivery.
Furthermore, in the prior art, ink must be carried to the fountain and poured or ladled in. The ink is in a trough, where it remains open to the air. Settling of contaminants is messy, requiring constant monitoring. Operators have to ladle in ink as the supply dwindles. If they miss a fountain with ink, or one is not filled at the proper time, additional waste results.
Color changes with existing presses require considerable time. It is necessary to remove the entire trough and clean it up. Ink disposal costs more and more money as environmental concerns mount. Initial adjustment takes an unreasonably long amount of time. Press preset, plating and ink/water setting take too long, and require the waste of too much paper using the cam or screw type adjusters. Skilled labor is required to adjust the old fashioned cam and screw type adjusters.
With individual, and preferably digital or volume ink control, it is possible to arrive at the correct setting within a short time, keeping customers that would be lost to other shops. With the arrangement of color towers, personnel have to climb stairways and ladders to achieve ink adjustment and ink control. The inventive digital ink system will create a revolution in the publishing trade.
The ability to carry the ink flow from zero to as much as is required and to have the ink flow proportioned to the line shaft, with a speed sensor, is a unique feature of the present invention. In a standard open fountain configuration, a metering blade is placed close to the ink drum and used to control ink flow from the reservoir. The blade scrapes an ink film of a given thickness, which varies throughout the length of the blade. Thus, the blade is placed in a different configuration as determined by the adjustment throughout its length. This is done by adjusting the blade gap between areas of different ink flow. As the press speed goes up, the ink delivery will vary accordingly.
In a digital injector system, the ink is not metered with a gap. Rather, it is pumped by a microprocessor controlled positive displacement injector in exact quantities. The transfer blade is not used to control flow, but only to spread the ink evenly across the control zone. Thus, the transfer blade is adjusted to a single constant distance from the roller and this distance is never changed.
As press speed varies, the pumps all adjust automatically to overcome the new ink flow requirement based on a column-to-column position for every part of the press. Press speed information is broadcast to each page pack, allowing this projection to be performed thousands of times every second. The result is unmatched precision and repeatability. In addition, the unit will track the requirement set out for that particular pump. Under conditions where no ink is required to be supplied to a particular zone, the transfer blade is still maintained at its contact distance from the roller, but the roller goes empty, because the pump supplies no ink to that zone.
The ink need not remain open to the air. It is delivered from the tank directly to the page pack inlet via permanently plumbed ink supply lines. There, it is dispersed to the individual chambers and pressurized by the individual injectors. It is sent out through the plastic tubing into the delivery head in precisely controlled quantities at exactly calculated flow rates. The ink train rollers move the ink away in exactly the same fashion as they did previously. The result is a smooth and even ink supply that tracks press speed changes so well it is truly a "set and forget" operation. In many cases, the operator can accurately present a print position by visually sizing the plate and pre-adjusting the ink settings.
In view of the failure of the prior art to provide a volume-controlled and preferably digital ink system for one or more presses, it is an object of the present invention to provide such a system.
Another object of the invention is to do away with individual adjustments for each part of the blade accompanying prior art systems.
A further object of the invention is to provide a system which is capable of varying the amount of ink delivered both in response to individual settings on an ink pump, and also to cause the amount of ink fed to be proportional to press speed.
Yet another object of the present invention is to provide a system wherein microprocessor based, computer driven accuracy and solid reliability can be attained job after job.
Still another object of the present invention is to provide a system wherein one or more columns have no ink whatsoever.
It is a further object of the invention to have permanently plumbed ink supplies which in turn can maintain the viscosity and keep the ink contaminant-free during operation.
Another object of the invention is to do away with open-to-the-air ink vats, which are also open to contamination.
A further object of the invention is to produce a press that is capable of responding to a change in the ink amounts delivered, without overshoot, undershoot or oscillating ink densities.
A still further object of the invention is to provide a system which will work with both heat set or cold set inks.
An additional object of the invention is to provide a replacement system of ink control which, is applicable to tower units of all kinds, including towers having several colors.
It is an object of the present invention to allow press personnel to be put to more profitable uses, inasmuch as "cross-training" becomes easier where ink adjustment is not an art known only to the journeyman.
Another object of the invention is to provide the ability to visually gauge and preset the press before the first cylinder turns.
Yet another object of the invention is to reduce waste and to provide more output for both the ink and the paper used in total.
A further object of the invention is doing away with the need to provide for electrical or mechanical adjustments once the system is set.
Another object of the invention, in some embodiments, is to provide a system which includes high speed, noise immune fiber optic communications.
Still another object of the invention is to provide a system which will track the consumption of inks used in various press runs.
Another object of the invention is to control the application of the ink volumetrically, as opposed to attempting to control the ink film thickness by a movable blade or the like.
A still further object of the invention is to control ink thickness by a volumetric control and thus avoid allowing water to dilute the thickness of the ink and vary the amount of actual ink used at a given setting of the press.
Another object of the invention is to provide an array of conversion parts which enables one to convert an existing press to a volume-based ink delivery system.
Another object of the invention would be to provide a system of digital ink pumps and their associated mechanism for supplying ink, and having the apparatus available as a kit to install on existing presses, without change to the remaining parts of the press.
Yet another object of the invention is to provide a method of replacing the ink baths with a digital volume-controlled inking system.
Still another object of the invention is to provide a new means of supplying ink to an older press, said method involving replacing the ink and feed mechanism, including their associated keyboard(s) and plural individual outlets for said each of the pumps, without change to the remainder of the press.
The foregoing and other objects of the invention are achieved in practice by providing a system which includes a page pack for use in a press, or one in a series of pages for each color, wherein the page pack includes plural ink pumps of the digital variety, and wherein there is a novel arrangement of ink feeding units, each fanning out and adapted to supply ink to a particular column of the paper being printed.
The manner in which the foregoing and other objects and advantages are achieved in practice will become more clearly apparent when reference is made to the following detailed description of the preferred embodiments of the invention set forth by way of example and shown in the accompanying drawings wherein like reference numbers indicate corresponding parts throughout.